1. Field of the Invention
The present invention relates to an up-and-down pulley device for suspension lamps, having considerable structural improvements in comparison with the up-and-down pulley devices presently used for the suspension of height adjustable lamps. Although in this description the term lamp will be always used, it is however to be noted that the up-and-down pulley device of the present invention may be used also to support any other article requiring an adjustable descent.
2. State of Prior Art
Several up-and-down pulley devices for suspension lamps are already known, but even the most improved devices available still have several drawbacks, among which are the noise caused by the internal mechanical members of the device during its operation, the defective blocking of the motion of the lamp suspension wire, as well as of the cable feeding to the lamp the electric current, the great number of elements of which the device consists, with the consequence of the high manufacturing cost, the lack of a universal system of attachment to the ceiling, and the possibility of detachment, misalignment or failure of some elements under stress.